Rotating vs Stationary Anode on C-Arm

Rotating vs Stationary anode system is becoming a hot topic in 2019 due to many new available systems coming out with stationary anode.  Stationary Anode was the main player on almost all C-Arms up until mid 90’s.  OEC 9400 which was built between 1990 and 1994 was equipped with 6kW Rotating Anode tube and every since then, Rotating anode was the main player of the C-Arm market with almost all system built every since equipped with Rotating Anode tube.

Rotating Anode Image from http://www.kailongx-ray.com/en/

Easily put, Rotating Anode system is more powerful, simply because the surface that X-ray tube is hitting before beaming out to be used is literary rotating versus stationary anode’s surface that X-ray tube hits with X-ray does not move.  While this doesn’t seem like much of a difference, result of this difference is power output.

When you have a rotating anode (surface where x-ray hits) it can take a LOT more heat & x-ray compare to stationary or same surface that does not move = allowing more powerful X-ray.

American average weight, Image from: https://www.washingtonpost.com/news/wonk/wp/2015/06/12/look-at-how-much-weight-weve-gained-since-the-1960s/

As average American getting heavier through the years, having rotating anode became a necessary on C-Arm system as stationary anode’s typical 110kV limit penetration on lateral shots of patients above 200 lbs.

Difference in Numbers:

Stationary Anode (typical figures)
2.2kW ~ 5kW
110kV max
10~15mA max

Rotating Anode (typical figures)
5kW ~ 25kW (or more)
120~125kV max
20~50+mA max

These numbers may not mean that much to you but here’s something that’s easier to understand.

OEC, who dominated C-Arm market for couple decades at least, always equipped rotating anode since OEC 9000 but we’re going to cover starting with 9400 in this article.  Below is all major system built by OEC since 9400, when it was manufactured and what type of anode it was equipped with.

OEC 9400 (1990-1994) – Rotating Anode
OEC 9600 (1994-1999) – Rotating Anode
OEC 9800 (1999-2006) – Rotating Anode
OEC 9900 (2006-present) – Rotating Anode
OEC CFD – (2017-present) – Rotating Anode

Every Single main system built by OEC since 1990 came with Rotating Anode tube.  Then come recently years, we are now seeing new systems from many manufactures that’s equipped with stationary anode as well as their main flagship model still equipped with Rotating Anode which is interesting.  And as far as I know, there has no report of how Americans are getting skinnier and we no longer need extra power of rotating anode.  I honestly do not know what’s the reason behind new C-Arm models equipped with Stationary Anode beside the fact that those systems are generally cheaper.

Older technology with lower output tends to be cheaper than newer technology with higher output, right?

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